Motor and brush device

ABSTRACT

A motor and a brush device are provided which allow an easy assembly of brush holders. The brush holders have fixing portions and brush accommodating portions integrally formed therewith. The fixing portions are secured to the gear case, and the brush accommodating portions slidably hold brushes. The motor has a gear case which is integrally formed with a reduction mechanism accommodating portion to accommodate a reduction mechanism and with a brush holder mounting portion in which the brush holders can be installed in a direction of an axis of the output shaft.

BACKGROUND OF THE INVENTION

[0001] Field of the Invention

[0002] The present invention relates to a motor and a brush device used in, for example, a sun roof drive unit in motor vehicles.

[0003] The motor and the brush device of this kind are known to have a construction in which a brush holder has its base end portion mounted to a holder base provided separately from a case and its front end portion attached with a brush. The brush is pressed against a commutator by the brush holder so that the brush is electrically connectable to the commutator.

[0004] In the motor and the brush device described above, however, since the brush holder is mounted to the holder base which is formed separately from the case, the assembly work cannot be performed easily.

[0005] It is an object of the present invention to provide a motor and a brush device which allow a very easy assembly of the brush holder.

SUMMARY OF THE INVENTION

[0006] According to a first aspect, the present invention provides a small motor which comprises: a motor case accommodating an armature, the armature being adapted to rotate when energized; a rotatable reduction mechanism receiving the rotation of the armature; an output shaft coupled to the reduction mechanism for rotation; a gear case connected to the motor case to rotatably support the output shaft; a brush electrically connectable to a commutator provided to the armature; a brush spring for pressing the brush against the commutator; and a brush holder installed in the gear case and slidably holding the brush; wherein the brush holder has a fixing portion and a brush accommodating portion integrally formed therewith, the fixing portion being secured to the gear case, the brush accommodating portion slidably holding the brush; wherein the gear case is integrally formed with a reduction mechanism accommodating portion for accommodating the reduction mechanism and with a brush holder mounting portion in which the brush holder can be installed in a direction of an axis of the output shaft.

[0007] According to a second aspect, the present invention provides a motor with the construction of the first aspect wherein the brush has a sliding portion and a tapered surface, the sliding portion being formed at almost a central part of the brush and protruding from a brush body to come into sliding contact with the commutator, the tapered surface adjoining the sliding portion and being arranged in a tapered configuration and adapted to contact the commutator and thereby increase an area of the brush in contact with the commutator as the wear of the sliding portion proceeds.

[0008] According to a third aspect, the present invention provides a motor with the construction of the first or second aspect wherein a pair of the brush and the brush accommodating portion has a temporary locking means which, when inserting the commutator, temporarily locks the brush at a predetermined position so that the commutator can be inserted and which, after the commutator has been inserted, unlocks the brush allowing the brush to come into electrical contact with the commutator.

[0009] According to a fourth aspect, the present invention provides a motor with the construction of the third aspect wherein the temporary locking means comprises a locking portion formed in the brush and a brush locking tongue piece formed in a part of the brush accommodating portion, the brush locking tongue piece being adapted to engage the locking portion of the brush when the commutator is inserted and, after the commutator has been inserted, to disengage from the locking portion.

[0010] According to a fifth aspect, the present invention provides a brush device which comprises: a brush electrically connectable to a commutator provided to an armature of a motor; and a brush holder secured to a case of the motor to hold the brush in such a way that the brush can be brought into sliding contact with the commutator; wherein the brush is formed with a sliding portion and a tapered surface, the sliding portion protruding from a brush body to come into sliding contact with the commutator, the tapered surface adjoining the sliding portion and being arranged in a tapered configuration and adapted to contact the commutator and thereby increase an area of the brush in contact with the commutator as the wear of the sliding portion proceeds.

[0011] According to a sixth aspect, the present invention provides a brush device with the construction of the fifth aspect wherein the tapered surface of the brush comprises first and second tapered surfaces arranged one on each side of the sliding portion formed at almost a center of the brush with respect to a direction of rotation of the commutator.

[0012] According to a seventh aspect, the present invention provides a brush device with the construction of the fifth or sixth aspect wherein the sliding portion of the brush has a curved surface.

[0013] According to an eighth aspect, the present invention provides a brush device with the construction of the fifth, sixth or seventh aspect wherein a pair of the brush and the brush accommodating portion has a temporary locking means which, when inserting the commutator, temporarily locks the brush at a predetermined position so that the commutator can be inserted and which, after the commutator has been inserted, unlocks the brush allowing the brush to come into electrical contact with the commutator.

[0014] According to a ninth aspect, the present invention provides a brush device with the construction of the eighth aspect wherein the temporary locking means comprises a locking portion formed in the brush and a brush locking tongue piece formed in a part of the brush accommodating portion, the brush locking tongue piece being adapted to engage the locking portion of the brush when the commutator is inserted and, after the commutator has been inserted, to disengage from the locking portion.

[0015] In the motor and the brush device according to this invention, the brush holder having a brush accommodating portion for slidably holding the brush is installed in a brush holder mounting portion of the gear case in a direction of an axis of the output shaft to securely fix the fixing portion of the brush holder to the gear case. Therefore, the brush holder does not require the holder base and can be mounted directly to the gear case.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a plan view showing an inner construction of a gear case of a motor in one embodiment of the motor and brush device according to the present invention.

[0017]FIG. 2 is an external perspective view of the motor of FIG. 1.

[0018]FIG. 3 is an external perspective view showing a mounting position of the brush device in the motor of FIG. 1.

[0019]FIG. 4 is a transverse cross section of the motor of FIG. 1.

[0020]FIG. 5 is an enlarged view of the brush device and its associated parts in the motor of FIG. 4.

[0021]FIG. 6 is a vertical cross section of a wheel gear and its associated parts in the motor of FIG. 1.

[0022]FIG. 7 is a vertical cross section showing positions of the brushes when a commutator is installed in the motor of FIG. 1.

[0023]FIG. 8 is a vertical cross section showing positions of the brushes when a commutator is installed in the motor of FIG. 1.

[0024]FIG. 9 is an external perspective view of a single brush used in the motor of FIG. 1.

[0025]FIG. 10 is an external perspective view of a single first brush holder in the motor of FIG. 1 as seen diagonally from above.

[0026]FIG. 11 is an external perspective view of the single first brush holder in the motor of FIG. 1 as seen diagonally from below.

[0027]FIG. 12 is an external perspective view, as seen diagonally from above, of the single first brush holder in the motor of FIG. 1 which holds a first brush.

[0028]FIG. 13 is an external perspective view, as seen diagonally from below, of the single first brush holder in the motor of FIG. 1 which holds a first brush.

[0029]FIG. 14 is an external perspective view of a single second brush holder in the motor of FIG. 1 as seen diagonally from above.

[0030]FIG. 15 is an external perspective view of the single second brush holder in the motor of FIG. 1 as seen diagonally from below.

[0031]FIG. 16 is an external perspective view, as seen diagonally from above, of the single second brush holder in the motor of FIG. 1 which holds a first brush.

[0032]FIG. 17 is an external perspective view, as seen diagonally from below, of the single second brush holder in the motor of FIG. 1 which holds a first brush.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0033]FIG. 1 through FIG. 17 illustrate one embodiment of the motor and brush device according to the present invention.

[0034] In the motor and brush device of this invention, a motor 30 comprises mainly a gear case 2, a motor case 3, first and second magnets 4, 5, an armature 6, a wheel gear 11, an output shaft 12, and a brush device 1. The brush device 1 includes first and second brushes 7, 8 and first and second brush holders 9, 10. The armature 6 includes an armature shaft 13, an armature core 14, a commutator 15 and an armature coil 16.

[0035] The gear case 2 has a flange portion 2 a, an armature shaft accommodating portion 2 b, a brush holder mounting portion 2 c, a wheel gear accommodating portion 2 d, a connector accommodating portion 2 e, and a reduction mechanism accommodating portion 2 f, all formed integral as one piece. The flange portion 2 a is secured to an open end of the motor case 3 with screws 17.

[0036] The armature shaft accommodating portion 2 b is formed cylindrical, extending from a central part of the flange portion 2 a toward the end of the gear case 2. As shown in FIG. 4, the armature shaft 13 of the armature 6 is inserted into the armature shaft accommodating portion 2 b. In the armature shaft accommodating portion 2 b, a first bearing 18 is arranged in the end portion of the gear case 2 and a second bearing 19 is arranged on the motor case side. The armature shaft accommodating portion 2 b is formed with first and second rectangular magnetic force linking holes 2 b 1, 2 b 2 at positions corresponding to a sensor magnet 22 mounted on the armature shaft 13. The brush holder mounting portion 2 c is arranged on the flange portion 2 a side of the armature shaft accommodating portion 2 b. The brush holder mounting portion 2 c is formed with a pair of first and second brush holder insertion holes 2 c 1, 2 c 2 through which the first and second brush holders 9, 10 are inserted. The first and second brush holder insertion holes 2 c 1, 2 c 2 are formed rectangular and extend through the armature shaft accommodating portion 2 b. The brush holder mounting portion 2 c is formed with a pair of first and second fixing portions 2 c 3, 2 c 4 to which first and second fixing pieces 9 a, 10 a formed on the first and second brush holders 9, 10 are secured. The first and second fixing portions 2 c 3, 2 c 4 comprise plate portions 2 c 5, 2 c 6 and notches 2 c 7, 2 c 8, as shown in FIG. 3. The brush holder mounting portion 2 c is formed with first and second protrusion insertion grooves 2 c 9, 2 c 10 in which a pair of protrusions 50 a, 50 b, formed on a brush unlocking jig 50 and arranged at positions corresponding to the first and second brush holder insertion holes 2 c 1, 2 c 2, are inserted.

[0037] The wheel gear accommodating portion 2 d is formed cylindrical and communicates with the interior of the armature shaft accommodating portion 2 b. The wheel gear accommodating portion 2 d accommodates the wheel gear 11 therein and is covered with a wheel gear cover 2 d 1 from outside. Formed at a central part of the wheel gear accommodating portion 2 d is a shaft support portion 2 d 2 fixedly attached with a third bearing 20, as shown in FIG. 6. The third bearing 20 rotatably supports an output shaft 12 formed integral with a rotating central portion of the wheel gear 11. The output shaft 12 is coupled, for example, to a sun roof drive unit.

[0038] The connector accommodating portion 2 e is located by the side of the wheel gear accommodating portion 2 d. A connector not shown is installed in the connector accommodating portion 2 e. Terminals of the connector are electrically connected to a control circuit on a printed circuit board not shown which is accommodated in the reduction mechanism accommodating portion 2 f. The reduction mechanism accommodating portion 2 f that accommodates the printed circuit board is covered with a gear case cover not shown.

[0039] First and second magnets 4, 5 are mounted on the inner side of a motor case body 3 a of the motor case 3. An end cover 3 b is attached to an end of the motor case body 3 a on the closed side. The end cover 3 b has a fourth bearing 21. In the motor case 3, the armature 6 is rotatably supported by the first and second magnets 4, 5 in a noncontact manner and by the first, second and fourth bearings 18, 19, 21.

[0040] The armature 6 has an armature core 14, a commutator 15 and a sensor magnet 22, all secured to the armature shaft 13. The armature core 14 is wound with an armature coil 16 electrically connected to the commutator 15. The armature shaft 13 inserted in the armature shaft accommodating portion 2 b of the gear case 2 has one part thereof near one end formed with a worm gear 13 that constitutes a reduction mechanism 40. The worm gear 13 is in mesh with a gear portion 11 a of the wheel gear 11 that also makes up the reduction mechanism 40.

[0041] The first and second brush holders 9, 10 are integrally formed with first and second fixing pieces 9 a, 10 a, first and second brush accommodating portions 9 b, 10 b, and third and fourth fixing pieces 9 c, 10 c. The first and second fixing pieces 9 a, 10 a are shaped like plates. The first fixing piece 9 a for the first brush holder 9, as shown in FIG. 10 to FIG. 13, is longer than the second fixing piece 10 a for the second brush holder 10 shown in FIG. 14 to FIG. 17. The first fixing piece 9 a is fitted into a notch 2 c 7 formed in the first fixing portion 2 c 3 of the brush holder mounting portion 2 c in the gear case 2 to fix the first brush holder 9 to the gear case 2. The second fixing piece 10 a is fitted into a notch 2 c 8 formed in the second fixing portion 2 c 4 of the brush holder mounting portion 2 c in the gear case 2 to fix the second brush holder 10 to the gear case 2. The first fixing piece 9 a has an L-shaped terminal portion 9 a 1 at its free end, and the second fixing piece 10 a has a linearly extending terminal portion 10 a 1 at its free end. The terminal portions 9 a, 10 a 1 are electrically connected to a control circuit on the printed circuit board. The third and fourth fixing pieces 9 c, 10 c are fitted into first and second brush holder insertion holes 2 c 1, 2 c 2 of the gear case 2.

[0042] First and second brushes 7, 8 are installed in the first and second brush accommodating portions 9 b, 10 b through first and second brush springs 23, 24. The first and second brushes 7, 8 accommodated in the first and second brush accommodating portions 9 b, 10 b are supported movable in a radial direction of the commutator 15, i.e., in a direction of cylinder axes of the first and second brush accommodating portions 9 b, 10 b. The first and second brush accommodating portions 9 b, 10 b have their bottoms formed with slits 9 b 2, 9 b 2 at a predetermined interval and slits 10 b 2, 10 b 2 at a predetermined interval. These slits 9 b 2, 9 b 2 and slits 10 b 2, 10 b 2 form first and second brush locking tongue pieces 9 b 1, 10 b 1. The first and second brush locking tongue pieces 9 b 1, 10 b 1 have elasticity at their free end or front end because of the slits 9 b 2, 9 b 2 and slits 10 b 2, 10 b 2. First and second projections 9 b 3, 10 b 3 are formed on the upper surfaces of the first and second brush locking tongue pieces 9 b 1, 10 b 1.

[0043] The first and second brush locking tongue pieces 9 b 1, 10 b 1 have their free front end portions 9 b 4, 10 b 4 arranged elastically deformable inwardly and outwardly of the brush accommodating portions, as shown in FIG. 11 and FIG. 15, with the brush insertion side taken as a base and the opposite side as a front. When the first and second brushes 7, 8 are inserted into the first and second brush accommodating portions 9 b, 10 b from their inlets, the first and second projections 9 b 3, 10 b 3 of the first and second brush locking tongue pieces 9 b 1, 10 b 1 fit into locking recesses 7 f, 8 f formed in the first and second brushes 7, 8, as shown in FIG. 7, thereby keeping the brushes 7, 8 from coming off the brush accommodating portions 9 b, 10 b. This arrangement temporarily locks the brushes when the commutator 15 is installed between the first and second brushes 7, 8. At this time, a space larger than the external diameter of the commutator 15 is formed between the first and second brushes 7, 8. With the commutator 15 installed in the space between the first and second brushes 7, 8, the protrusions 50 a, 50 b of the brush unlocking jig 50 are inserted into the first and second protrusion insertion grooves 2 c 9, 2 c 10 in the gear case 2. The protrusions 50 a, 50 b push the front end portions 9 b 4, 10 b 4 of the first and second brush locking tongue pieces 9 b 1, 10 b 1 to disengage the first and second projections 9 b 3, 10 b 3 of the first and second brush locking tongue pieces 9 b 1, 10 b 1 from the locking recesses 7 f, 8 f of the first and second brushes 7, 8. As a result, the first and second brushes 7, 8 are pressed against the commutator 15 for electric connection by elastic recovering forces of the first and second brush springs 23, 24. Since the first and second brushes 7, 8 are pressed against the commutator 15 by the first and second brush springs 23, 24, the locking recesses 7 f, 8 f of the first and second brushes 7, 8 that were disengaged from the first and second projections 9 b 3, 10 b 3 are prevented from being locked again by the first and second projections 9 b 3, 10 b 3. Then, the protrusions 50 a, 50 b of the brush unlocking jig 50 are drawn out from the first and second protrusion insertion grooves 2 c 9, 2 c 10 of the gear case 2.

[0044] As shown in FIG. 7 and FIG. 9, the first and second brushes 7, 8 have first and second pig tails 7 b, 8 b electrically connected at one end to the brush bodies 7 a, 8 a and at the other end to-the third and fourth fixing pieces 9 c, 10 c. The brush bodies 7 a, 8 a are formed with a pair of first and second tapered surfaces 7 d, 7 e, 8 d, 8 e on both sides of slide contact portions 7 c, 8 c pressed against the commutator 15. The brush bodies 7 a, 8 a are formed at their bottom surfaces with the locking recesses 7 f, 8 f that constitute a temporary holding means 31. The slide contact portions 7 c, 8 c have curved surfaces 7 c 1, 8 c 1, respectively, that are curved along the axis of the armature shaft 13. The first and second brushes 7, 8 are in sliding contact with the commutator 15 mainly through the slide contact portions 7 c, 8 c protruding from the brush bodies 7 a, 8 a. As the slide contact portions 7 c, 8 c of the first and second brushes 7, 8 wear, the first and second tapered surfaces 7 d, 7 e, 8 d, 8 e also come into contact with the commutator 15, thus increasing the contact surfaces of the first and second brushes 7, 8. The first and second tapered surfaces 7 d, 7 e, 8 d, 8 e have a function of progressively increasing the contact area with the commutator 15 as the wear of the first and second brushes 7, 8 proceeds. The slide contact portions 7 c, 8 c of the first and second brushes 7, 8 are formed at their upper and lower ends with cut portions 7 g, 7 g, 8 g, 8 g that also cover the upper and lower ends of the first and second tapered surfaces 7 d, 7 e, 8 d, 8 e. The cut portions 7 g, 7 g, 8 g, 8 g have a function of eliminating troubles, such as the brushes getting caught by the commutator 15 during sliding contact, that may result if the brushes should tilt in the first and second brush accommodating portions 9 b, 10 b of the first and second brush holders 9, 10.

[0045] The motor 30 and brush device 1 of a construction described above are used as follows. They are mounted on a car body, with the gear case 2 of the motor 30 secured to a roof inner panel of the car, with the output shaft 12 of the wheel gear 11 coupled to the sun roof drive unit, and with the connector of the sun roof control circuit installed in the connector accommodating portion 2 e of the gear case 2. When, with a sun roof lid closed, the sun roof control circuit is switched to the lid opening side, the armature shaft 13 and the wheel gear 11 start to rotate in a forward direction, transmitting their force through the output shaft 12 to the sun roof drive unit which then opens the sun roof lid. When, with the sun roof lid open, the sun roof control circuit is switched to the lid closing side, the armature shaft 13 and the wheel gear 11 start to rotate in a reverse direction, transmitting the force through the output shaft 12 to the sun roof drive unit which then closes the sun roof lid.

[0046] As described above, the first and second brushes 7, 8 are in sliding contact with the commutator 15 mainly through the slide contact portions 7 c, 8 c protruding from the brush bodies 7 a, 8 a. As the slide contact portions 7 c, 8 c of the first and second brushes 7, 8 wear, the first and second tapered surfaces 7 d, 7 e, 8 d, 8 e also come into contact with the commutator 15, gradually increasing the area of the brushes in contact with the commutator 15. Therefore, at first the first and second brushes 7, 8 are in sliding contact with the commutator 15 through a small contact area and, as the wear progresses, the contact area with the commutator 15 progressively increases. Thus, a sharp change in the contact area is prevented. The first and second brush holders 9, 10 for slidably holding the first and second brushes 7, 8 in their first and second brush accommodating portions 9 b, 10 b are installed in the brush holder mounting portion 2 c of the gear case 2 in a direction of the axis of the output shaft 12, so that the first and second fixing pieces 9 a, 10 a of the first and second brush holders 9, 10 are firmly secured to the gear case 2.

[0047] As described above, with the motor and brush device of this invention, since the brush holders for slidably holding the brushes in their brush accommodating portions are installed in the brush holder mounting portion of the gear case in a direction of the axis of the output shaft, the fixing pieces of the brush holders are firmly secured to the gear case. Therefore, the brush holders do not require holder bases and can be mounted directly to the gear case, thus offering the advantage of being able to perform the assembly of the brush holders very easily. 

What is claimed is:
 1. A small motor comprising: a motor case accommodating an armature, the armature being adapted to rotate when energized; a rotatable reduction mechanism receiving the rotation of the armature; an output shaft coupled to the reduction mechanism for rotation; a gear case connected to the motor case to rotatably support the output shaft; a brush electrically connectable to a commutator provided to the armature; a brush spring for pressing the brush against the commutator; and a brush holder installed in the gear case and slidably holding the brush; wherein the brush holder has a fixing portion and a brush accommodating portion integrally formed therewith, the fixing portion being secured to the gear case, the brush accommodating portion slidably holding the brush; wherein the gear case is integrally formed with a reduction mechanism accommodating portion for accommodating the reduction mechanism and with a brush holder mounting portion in which the brush holder can be installed in a direction of an axis of the output shaft.
 2. A motor according to claim 1, wherein the brush has a sliding portion and a tapered surface, the sliding portion being formed at almost a central part of the brush and protruding from a brush body to come into sliding contact with the commutator, the tapered surface adjoining the sliding portion and being arranged in a tapered configuration and adapted to contact the commutator and thereby increase an area of the brush in contact with the commutator as the wear of the sliding portion proceeds.
 3. A motor according to claim 1 or 2, wherein a pair of the brush and the brush accommodating portion has a temporary locking means which, when inserting the commutator, temporarily locks the brush at a predetermined position so that the commutator can be inserted and which, after the commutator has been inserted, unlocks the brush allowing the brush to come into electrical contact with the commutator.
 4. A motor according to claim 3, wherein the temporary locking means comprises a locking portion formed in the brush and a brush locking tongue piece formed in a part of the brush accommodating portion, the brush locking tongue piece being adapted to engage the locking portion of the brush when the commutator is inserted and, after the commutator has been inserted, to disengage from the locking portion.
 5. A brush device comprising: a brush electrically connectable to a commutator provided to an armature of a motor; and a brush holder secured to a case of the motor to hold the brush in such a way that the brush can be brought into sliding contact with the commutator; wherein the brush is formed with a sliding portion and a tapered surface, the sliding portion protruding from a brush body to come into sliding contact with the commutator, the tapered surface adjoining the sliding portion and being arranged in a tapered configuration and adapted to contact the commutator and thereby increase an area of the brush in contact with the commutator as the wear of the sliding portion proceeds.
 6. A brush device according to claim 5, wherein the tapered surface of the brush comprises first and second tapered surfaces arranged one on each side of the sliding portion formed at almost a center of the brush with respect to a direction of rotation of the commutator.
 7. A brush device according to claim 5 or 6, wherein the sliding portion of the brush has a curved surface.
 8. A brush device according to claim 5, 6 or 7, wherein a pair of the brush and the brush accommodating portion has a temporary locking means which, when inserting the commutator, temporarily locks the brush at a predetermined position so that the commutator can be inserted and which, after the commutator has been inserted, unlocks the brush allowing the brush to come into electrical contact with the commutator.
 9. A brush device according to claim 8, wherein the temporary locking means comprises a locking portion formed in the brush and a brush locking tongue piece formed in a part of the brush accommodating portion, the brush locking tongue piece being adapted to engage the locking portion of the brush when the commutator is inserted and, after the commutator has been inserted, to disengage from the locking portion. 